“As children develop physically, it changes how they think
about themselves and how people relate to them socially,” says
Jane Mendle, PhD, a psychologist at Cornell University.

For young people who begin puberty earlier than their
peers, the transformation appears to be particularly fraught
— especially for girls. Early-maturing girls are at increased
risk of a range of psychosocial problems including depression,
substance use and early sexual behavior, as University of
Florida psychologist Julia Graber, PhD, described in a recent
review (Hormones and Behavior, 2013). The picture for early-developing boys isn’t as clear, but evidence suggests that they,
too, might suffer ill effects from maturing ahead of their peers.

That’s worrisome, especially because the average age ofpuberty seems to be trending younger for children worldwide.

The average age of a girl’s first period in the United States and
Europe was about 16 a century ago. Today, it’s closer to 13, as
Susan Euling, PhD, and colleagues described in a 2008 paper
(Pediatrics, 2008). Far fewer studies have explored pubertal
timing in boys, in part because there isn’t a clear objective
marker of puberty in boys comparable to a girl’s first period.

Still, some studies have suggested that boys, too, might be
developing earlier than generations past.